US5245403A - Apparatus for detecting extraneous substances on a glass plate - Google Patents

Apparatus for detecting extraneous substances on a glass plate Download PDF

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US5245403A
US5245403A US07/813,837 US81383791A US5245403A US 5245403 A US5245403 A US 5245403A US 81383791 A US81383791 A US 81383791A US 5245403 A US5245403 A US 5245403A
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laser beam
extraneous substance
glass plate
elevation angle
light
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Noboru Kato
Izuo Horai
Toshihiro Kimura
Mitsuyoshi Koizumi
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Hitachi High Tech Corp
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Hitachi Electronics Engineering Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/47—Scattering, i.e. diffuse reflection
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/94—Investigating contamination, e.g. dust
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/47—Scattering, i.e. diffuse reflection
    • G01N2021/4792—Polarisation of scatter light
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/8851—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges
    • G01N2021/8854—Grading and classifying of flaws
    • G01N2021/8867—Grading and classifying of flaws using sequentially two or more inspection runs, e.g. coarse and fine, or detecting then analysing
    • G01N2021/887—Grading and classifying of flaws using sequentially two or more inspection runs, e.g. coarse and fine, or detecting then analysing the measurements made in two or more directions, angles, positions
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
    • G01N2021/9513—Liquid crystal panels
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
    • G01N21/9501—Semiconductor wafers

Definitions

  • the present invention relates generally to apparatus for detecting extraneous substances on an glass plates, and more particularly to an apparatus for detecting extraneous substances on a glass plate so that when extraneous substances are sticking to the front surface and the back surface of the glass plate, the extraneous substance sticking to the front surface thereof can be distinguished from what is sticking to the back surface before being detected.
  • Flaw inspecting apparatus are generally used for detecting extraneous substances sticking to the surfaces of masking substrates (glass substrates) and silicon wafers for use in manufacturing semiconductor ICs, and to glass plates for use in liquid crystal panels and the like, the extraneous substances ordinarily including flaws such as defects of their surfaces themselves. Product quality is thus maintained at not lower than a certain level.
  • FIG. 5 shows a basic configuration of a flaw detecting optical system in an apparatus for detecting wafer surface flaws as a flaw inspecting apparatus of the sort described above by way of example.
  • the optical system consists of a light projecting system 2 and a light receiving system 3. Laser beams emitted from a laser beam source 21 are focused by a light projecting lens 22. An optical spot is formed on the surface of a wafer plate 1 as an object under examination. When the optical spot scans the surface of the wafer plate 1 pursuant a revolving scanning or XY scanning method, it will be scattered at a place where a flaw is found. The scattered light is condensed by a condenser lens 31 in the light receiving system 3 and received by a light receiver 32. A flaw detection signal is thus obtained.
  • a stopper 33 provided in the light receiving system 3 is inserted for improving the S/N ratio by cutting off the regular reflected light deriving from the laser beam.
  • a TFT-type liquid crystal panel is formed with an extra-fine liquid crystal pixel electrode and a thin-film transistor (TFT), formed by etching the surface of a glass plate.
  • TFT thin-film transistor
  • the surface of the glass plate (glass substrate) with the liquid crystal pixel electrode and TFT formed thereon is provisionally called a pixel formative plane, for instance.
  • the glass substrate having a pixel formative plane is a plate which is translucent, as thin as about 1 mm and has high transmittance. Consequently, the problem is that extraneous substances sticking to the pixel formative plane (hereinafter simply called ⁇ surface extraneous substance(s) ⁇ ) and those sticking to the back surface of the glass substrate (hereinafter simply called ⁇ back surface extraneous substance(s) ⁇ ) may simultaneously be detected.
  • the back surface of the glass substrate is normally used as a side where an image to be displayed is observed or where back light is transmitted therethrough when the glass substrate is assembled as part of a liquid crystal panel.
  • the back surface of the glass substrate is only need to be a glass surface, and so long as extraneous substances sticking thereto are minute, they pose no problems; in other words, the extraneous substances are not regarded as flaws in many cases. In case these extraneous substances are detected as flaws, the otherwise good parts are assumed to be bad and the yield of parts tends to decrease, thus resulting in a heavy loss.
  • a flaw detecting signal concerning an extraneous substance, including a flaw, sticking to the surface.
  • FIG. 3(b) refers to cases where an extraneous substance Ps is sticking to the surface of the glass substrate 1 and where an extraneous substance Pb is sticking to the back surface thereof.
  • the light receiving system 3 on the surface side directly receives scattered light Rs deriving from the laser beam T at the surface extraneous substance Ps, and simultaneously irregular reflected light at the extraneous substance Pb on the back surface side.
  • scattered light Rb at the extraneous substance Pb on the back surface side passes through the glass substrate 1 and reaches the light receiving system 3. Due to total reflection, the scattered light Rb attenuates as it passes through the glass substrate 1.
  • the extraneous substance Ps on the surface side imparts to the light receiving system 3 scattered light that is more intense than what is directed to the light receiving system 3' on the back surface.
  • the light receiving system 3' on the back surface side directly receives scattered light Rb' deriving from the laser beam T' at the extraneous substance Pb on the back surface side, and simultaneously irregular reflected light at the extraneous substance Ps on the surface side.
  • scattered light Rs' at the surface extraneous substance Ps passes through the glass substrate 1 and reaches the light receiving system 3'.
  • the scattered light Rs' also attenuates as it passes through the glass substrate 1.
  • the extraneous substance Pb on the back surface side imparts to the light receiving system 3' scattered light more intense than what is directed to the light receiving system 3 on the surface side.
  • a comparison of the detected signals on both sides to find which one of the light receiving systems 3, 3', is receiving light that is more intense than the other makes it possible to determine whether the extraneous substance in question is located on the surface or the back surface side.
  • the present inventors have primarily given careful consideration to the prior art indistinguishability of respective extraneous substances on the surface and back surface sides when the above decision-making principle is actually applied, and have reasoned that the principle is based on a tacit understanding that the directivity of scattered light at the extraneous substance is uniform and omnidirectional. Referring to FIGS. 7(a), 7(b), a description will be given of this problem.
  • FIG. 7 shows the results of experiments made on the directivity of scattered light at an extraneous substance.
  • the intensity of scattered light R at an extraneous substance P in the direction of an angle ⁇ from the direction of projection of a laser beam T is considered first.
  • FIG. 7(b) shows experimental results by way of example. More specifically, FIG. 7(b) shows curves of the intensity F of scattered light at the angle ⁇ (°) with the particle diameter as a parameter (1-10 ⁇ m).
  • the intensity F of the scattered light drastically varies with the angle ⁇ .
  • the intensity is about 150 times greater in the direction of 90° (sideward).
  • the particle diameter is 10 ⁇ m, it is greater by about three digits in the direction of 90° (sideward).
  • the decision-making principle is appraised on the assumption that a light receiving system 3 has an angle as shown in FIG. 6(a).
  • forward scattered light deriving from a laser beam T' and undergoing total reflection within a liquid crystal panel 1 rather than scattered light Rs deriving from the laser beam T at a surface extraneous substance Ps, may be received more intensely by the light receiving system 3.
  • the forward scattered light deriving from the laser beam T, rather than scattered light Rb' deriving from the laser beam T' at an extraneous substance Pb on the back surface, may likewise be received more intensely by a light receiving system 3'.
  • an apparatus for detecting extraneous substances on a glass plate comprises a first light projecting system arranged above a plane (hereinafter called the ⁇ surface ⁇ ) to be inspected of a glass plate, the surface of which is irradiated with an S-polarized laser beam at a first elevation angle.
  • a second light projecting system is arranged above the surface thereof for irradiating the surface with a P-polarized laser beam at a second elevation angle greater than the first elevation angle, and a light receiving system is provided for receiving scattered light from the surface irradiated with the laser beams respectively emitted from the first and the second light projecting system at an elevation angle smaller than the first elevation angle.
  • the light receiving system is arranged on a side opposite to the direction of irradiation with the normal line set up at the laser beam irradiation point therebetween, and the output level of the P-polarized laser beam is set in specific relation to the S-polarized laser beam.
  • the presence of an extraneous substance on the surface is ultimately detected when a signal level obtainable in the light receiving system in response to the irradiation of the S-polarized laser beam is higher than a signal level obtainable in the light receiving system in response to the irradiation of the P-polarized laser beam.
  • the specific relation described above refers to a case where the output level of the P-polarized laser beam is set in such a way that a third and a fourth detection level are held between a first and a second detection level, wherein when an extraneous substance having a certain particle diameter on the surface is irradiated with the S-polarized laser beam, the level of the scattered light detected by the light receiving system is defined as the first detection level; wherein when the extraneous substance is irradiated with the S-polarized laser beam via the glass plate with its surface down, the level of the scattered light detected by the light receiving system is defined as the second detection level; wherein when the extraneous substance is irradiated with the P-polarized laser beam, the level of the scattered light detected by the light receiving system is defined as the third detection level; and wherein when the extraneous substance is irradiated with the P-polarized laser beam via the glass plate with its surface down, the level of the scattered light detected by the light receiving system is defined as the fourth detection level
  • the first and second light projecting systems should preferably be provided above and opposite to the surface (pixel formative plane) of the glass substrate at the following angles:
  • a light receiving system should be provided at a reception angle of about 10° perpendicular to the surface.
  • the first light projecting system should be set at an elevation angle of about 20° as a projection angle and the second light projecting system at an elevation angle of about 7° as a projection angle.
  • the laser beam power of the second light projecting system is set in the range of 2-4 times the irradiation power of the laser beam of the first light projecting system.
  • an object of the present invention is to provide an apparatus for detecting extraneous substances on a glass plate that has light projecting systems and a light receiving system on one side of the glass plate and is capable of detecting an extraneous substance on either the surface or the back surface of the glass plate separately from what is on the other.
  • Another object of the present invention is to provide an apparatus for detecting extraneous substances on a glass plate that has light projecting systems and a light receiving system on one side of the glass plate and is capable of detecting an extraneous substance on the surface of the glass plate separately from what is on the back surface thereof.
  • Still another object of the present invention is to provide an apparatus for detecting extraneous substances on a glass substrate that has light projecting systems and a light receiving system above a pixel formative plane and is capable of detecting an extraneous substance on the pixel formative plane side of the glass substrate for use in a liquid crystal panel separately from what is on the back surface side thereof.
  • a further object of the present invention is to provide an apparatus for detecting flaws of a glass plate that has light projecting systems and a light receiving system on one side of the glass plate and is capable of detecting a flaw on the surface side of the glass plate separately from what is on the back surface side thereof.
  • FIG. 1 is a diagram illustrating a configuration of an apparatus for detecting extraneous substances on the surface of a glass plate according to the present invention.
  • FIG. 2 is a diagram illustrating a model optical detecting system constructed according to the teachings of the present invention.
  • FIGS. 3(a) and 3(b) show experimental data indicating different detection voltages of a photoelectric converter element with respect to an extraneous substance having the same particle diameter on the surface or the back surface in the optical system model of FIG. 2, and curves exhibiting the reflection factor and transmittance of a glass substrate.
  • FIG. 5 is a diagram illustrating a basic configuration of an optical system in a conventional apparatus for detecting wafer surface flaws.
  • FIGS. 6(a) and 6(b) are diagrams illustrating a schematic configuration of the principle of separately detecting extraneous substances on both sides.
  • FIGS. 7(a) and 7(b) are diagrams illustrating the directivity of scattered light at an extraneous substance in the direction of projection of a laser beam.
  • an apparatus 10 for detecting surface extraneous substances on a glass plate has a laser source 41 for generating an S-polarized laser beam T A (s) and a laser source 42 for generating a P-polarized laser beam T B (p) by means of a semiconductor laser element, both the sources being located above a glass substrate 1, as an object under examination, such as a liquid crystal panel.
  • An irradiation control circuit 53 drives the laser sources 41, 42 alternately and causes them to generate the S-polarized laser beam T A (s) and P-polarized laser beam T B (p) alternately.
  • the irradiation control circuit 53 is controlled by a decision processing unit 55, which also interlockingly controls the driving of the laser sources and the rotation of a rotary mirror 44.
  • the P-polarized laser beam T B (p) has power k times (2-4 times) greater than that of the laser beam T A (s).
  • the mirror 47 is irradiated with each of the laser beams T A (s), T B (p) via a collimator lens 43, a rotary mirror 44 and a lens 45, and each laser beam is subjected to collimation, angle sweep and focusing commonly and successively via these optical systems. As a result, an optical spot is formed on the surface (pixel formative plane) of the glass plate 1 and used for surface scanning.
  • the laser beam T A (s) thus focused is changed in direction by two of the mirrors 461, 462 and projected onto the surface of the glass substrate at a projection angle (elevation angle) of about 20°.
  • the laser beam T B (p) is changed in direction by the mirror 47 and projected at a projection angle (elevation angle) of about 70° for scanning the same straight line that is scanned by the laser beam T A (s) on the glass substrate 1.
  • the irradiation control circuit 53 synchronously controls the period of the alternate driving of the laser sources 41, 42 and the rotating speed of the rotary mirror 44 for scanning purposes.
  • Scattered light obtainable at an extraneous substance at the time of laser beam irradiation is received by a light receiving system 5 situated at a reception angle (elevation angle) of about 10° with respect to the surface of the glass substrate 1.
  • the scattered light is condensed by a bundle 51 of optical fibers and the light thus condensed is supplied to a photoelectric converter element 52 in which it is converted into an electric signal.
  • Detected voltage corresponding to the quantity of light received is produced from the photoelectric converter element 52.
  • the detected voltage is divided into detected voltages R A , R B in accordance with the timing at which the driving of the laser source is controlled by the irradiation control circuit 53, and these voltages are sampled by an A/D converter circuit 54.
  • the sampling timing in the A/D converter circuit 54 is controlled by the decision processing unit 55 as well as the irradiation control circuit 53.
  • Each of the detected voltage values resulting from the conversion implemented in the A/D converter circuit 54 correspondingly after laser beam irradiation is read by a microprocessor (MPU) 56 and stored in a memory 57 in the decision processing unit 55.
  • the storage operation is performed together with the relevant scanning position (position coordinates on the X- and Y-planes of the glass substrate 1) on the glass substrate 1.
  • the decision processing unit 55 subsequently executes a predetermined decision processing program to obtain the difference between the detected voltages and decides whether they are equal or which of them is greater.
  • the decision processing unit 55 further decides the presence of a surface extraneous substance when both voltages are equal or when one of them is greater. In this case, data intended for use in computing the difference between the voltage values are concerned with what is higher than noise level.
  • the light receiving system for receiving the scattered light is arranged at a reception angle of about 10° in the forward direction of light reception.
  • the quantity of scattered light incident on the light receiving system 5 out of the scattered light in front of the surface extraneous substance due to the laser beam T A (s) is consequently large.
  • scattered light in front of the back surface extraneous substance due to the laser beam T A (s) considerably attenuates because of internal reflection within the glass substrate.
  • the quantity of transmitting light is generally smaller than that of reflected light in the S-polarized laser beam, scattered light originating from the back surface extraneous substance and entering the light receiving system located on the surface side is small in quantity and therefore the difference between the detected voltages tends to increase.
  • the voltage detected in the light receiving system 5 with the irradiation of the laser beam T A (s) is represented by R A , and the voltage detected therein with the irradiation of the laser beam T B (p), by R B .
  • R A the voltage detected when a surface extraneous substance is detected
  • R Ab the voltage detected when a back surface extraneous substance is detected
  • the voltage detected when a surface extraneous substance is detected is represented by R Bs and the voltage detected when a back surface extraneous substance is detected, by R Bb .
  • the light irradiation power of the laser beam T A (s) and the laser beam T B (p) directed to the surface of the glass substrate 1 is equal, the following relation is established among the detected voltages when the order of their intensity is considered:
  • FIG. 3 shows it is obtainable from measurement that the detected voltages remain in the above size relation.
  • Ps indicates standard particles of various particle diameters sticking to the surface of the glass substrate 1.
  • a plurality of standard particles sticking to the surface are made to constitute the surface extraneous substance Ps and then the glass substrate 1 is turned upside down to make the surface extraneous substance a back surface extraneous substance.
  • the surface and the back surface may be examined in such a state that an extraneous substance of the same variety is sticking to both sides.
  • the detected voltages (R As , R Ab ), (R Bs , R Bb ) of scattered light at the extraneous substance on the surface or the back surface in response to the irradiation of the laser beams T A (s), T B (p) are obtained alternately from the light receiving system 5.
  • data shown in FIG. 3(a) were obtained.
  • ⁇ A , ⁇ B represent detected voltages corresponding to the logarithmic difference between irregular reflection from the surface and reflection from the back surface in response to the irradiation of the laser beams T A (s), T B (p), respectively.
  • ⁇ A designates the mean value of the logarithmic difference between the detected voltages R As , R Ab with the irradiation of the laser beam T A (s)
  • ⁇ B designates the mean value of the logarithmic difference between the detected voltages R Bs , R Bb with the irradiation of the laser beam T B (p).
  • ⁇ A indicates a difference of one digit or greater between the detected voltages
  • ⁇ B indicates a difference of less than one digit therebetween.
  • the detected voltage R As shows a maximum value at any point as shown in data on each of the particle diameters (3 ⁇ m, 6.4 ⁇ m and 25 ⁇ m).
  • the back surface extraneous substance Pb also causes intense forward scattered light, it conforms to the value (1/ ⁇ A as illustrated) of the detected voltage R Ab (marked with ⁇ ) as it considerably attenuates because of internal reflection within the glass substrate.
  • the plurality of particles are tested and the results marked with symbol * (25 ⁇ m) designate detected voltages relating to one and the same particle.
  • the detected voltages relating to the other particles are substantially arranged in order, the data are considered sufficiently reliable. Then the mean value of those detected voltages is obtained and straight lines of the detected voltages R As , R Bs , R Ab and R Bb are regarded as those indicating representative values.
  • the actual values ⁇ A ⁇ 17, ⁇ B ⁇ 6 differ from each other.
  • the main reason for this is that the laser beams T A (s), T B (p) are S-polarized and a P-polarized light waves, respectively.
  • FIG. 3(b) shows transmittance curves of polarized light waves with respect to a glass substrate for use in a generally known liquid crystal panel.
  • the S-polarized light wave incident at an incident angle ⁇ (°) is reflected from the surface of the glass substrate and the reflection factor of power is indicated with a dotted line of E(s).
  • the reflection factor of power of the P-polarized light wave is indicated with E(p).
  • the reflection factor of the S-polarized laser beam is greater than that of the P-polarized one with the incident angle ranging from about 20° to about 85° in the case of the glass substrate for use in a liquid crystal panel.
  • the decision processing unit 55 decides the presence of the surface extraneous substance when R A -R B is positive in value or when R A /R b is not less than 1; it is acceptable to presume the presence of the back surface extraneous substance from the result in reverse.
  • the output of the laser beam T B (p) may be switched selectively in such a way that it becomes k (2-4) times greater in intensity than that of laser beam T A (s).
  • the detected voltages R Bs , R Bb deriving from the laser beam T B (p) are then equally set to be k times greater.
  • the multiple k is very important in the sense that the order of the detected voltage in size is varied as shown in FIG. 4(a).
  • the overall operation of the apparatus for detecting a surface extraneous substance on a glass substrate as shown in FIG. 1 comprises the following steps.
  • the decision processing unit 55 causes the surface of the glass substrate 1 to be irradiated with the laser beam T A (s) and the laser beam T B (p) having an output k times greater so as to scan the surface of the glass substrate 1 to collect voltage R with respect to scattered light in response to the scanning position, so that the respective results are stored in the memory 57.
  • MPU 56 obtains the difference between the detected voltages R A , R B with respect to the same scanning position.
  • the process of deciding the presence of such a surface or back surface extraneous substance by means of the decision processing unit 55 may comprise the steps of collecting data on either of the detected voltages R A or R B corresponding to respective measurement coordinates on the glass substrate 1 beforehand, storing the resulting data in the memory 57, storing the detected data on the opposite side in the memory 57, and reading the detected data on the detected voltages R A or R B that have been collected correspondingly.
  • angles at which two of the light projecting and receiving systems are installed only need to basically satisfy Eq. (3) in detection of extraneous substances or flaws.
  • a glass substrate for use in a liquid crystal panel roughly ranging from one to several millimeters in thickness, its angle is set in an elevation angle range smaller by about 2° than that of the elevation angle of the light projecting system of the laser beam T A (s) in order for the regular reflected light from the light projecting system of the laser beam T A (s) to be unreceivable.
  • the detected voltage whose level exceeds the noise level is generated even though there is no extraneous substance, as shown in the S/N ratio shown in FIG. 4(b), when the difference between the elevation angle of the light receiving system and those of projecting systems decreases to 2° or less.
  • the extraneous substance detection level on the back surface side is lower than that on the surface side. Consequently, the back surface extraneous substance S/N ratio that has been taken reveals the fact that, as shown in FIG. 4(c) illustrating the S/N ratio in the characteristics of (R As /R Bs ) ⁇ (R Bb /R Ab ), the irregular reflection from the back surface of the glass substrate exceeds the noise level and is received if the light receiving system is situated at an angle of 5° or greater even when there exists no back surface extraneous substance.
  • the detected output on the back surface side becomes excessive when any extraneous substance exists on the back surface and a value of (R As /R Bs ) ⁇ (R Bb /R Ab ) decreases to 1.5 or less, thus making it difficult to separate both sides from each other.
  • the elevation angle of the light receiving system should preferably substantially range from 5° to 15°. As a result, it is preferred for the light projecting system of the laser beam T A (s) to be angled at 7° or larger.
  • the difference in elevation angle between the light projecting systems relating to the respective laser beams T A (s), T B (p) should be not less than 50° to make the difference between the detected voltages R A and R B about one digit or greater in responsive to the irradiation of the laser beam T A (s). Therefore, the angle of the light projecting system relating to the laser beam T A (s) should be set at not more than 25°. In other words, the angle of light projecting system relating to the laser beam T A (s) should preferably range from 7° to 25°, whereas what relates to the laser beam T.sub. B (p) should preferably range from 57° to 75°.
  • the more preferable range empirically considered is such that the light receiving system should be provided at an elevation angle of about 10° ⁇ 3°. Any extraneous substance may be detected in such a preferable state as what is understood in reference to the angle setting shown in the embodiment above, wherein with respect to the projection angle of the laser beam T A (s), it is set at an elevation angle of about 20° ⁇ 3° and with respect to that of the laser beam T B (p), it is set at an elevation angle of about 70° ⁇ 3°.

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US07/813,837 1990-12-27 1991-12-27 Apparatus for detecting extraneous substances on a glass plate Expired - Lifetime US5245403A (en)

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JP2-414979 1990-12-27
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Cited By (34)

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US5412221A (en) * 1994-04-26 1995-05-02 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Particle fallout/activity sensor
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US20060007435A1 (en) * 1997-09-19 2006-01-12 Steve Biellak Systems and methods for a wafer inspection system using multiple angles and multiple wavelength illumination
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US6433353B2 (en) * 1998-08-31 2002-08-13 Central Glass Company, Limited Method and apparatus for inspecting surface irregularities of transparent plate
US6376829B1 (en) * 1998-08-31 2002-04-23 Central Glass Company, Limited Method of and apparatus for inspecting surface irregularities of transparent plate
US20050134841A1 (en) * 1998-09-18 2005-06-23 Mehdi Vacz-Iravani Sample inspection system
US20040057045A1 (en) * 2000-12-21 2004-03-25 Mehdi Vaez-Iravani Sample inspection system
WO2003001185A1 (fr) * 2001-06-25 2003-01-03 Kla-Tencor Corporation Systemes et procedes d'inspection de substrats de masque transparent
US20040233403A1 (en) * 2001-09-21 2004-11-25 Detlef Gerhard Device and method for optically scanning a substrate disk
US6992316B2 (en) 2002-06-21 2006-01-31 Applied Materials, Inc. Angled sensors for detecting substrates
US20040051060A1 (en) * 2002-06-21 2004-03-18 Shinichi Kurita Angled sensors for detecting substrates
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US20110157581A1 (en) * 2004-06-28 2011-06-30 Christopher Davies Investigation of Vehicle Glazing Panels
US7868291B2 (en) 2004-06-28 2011-01-11 Carglass Luxembourg Sarl-Zug Branch Investigation of vehicle glazing panels
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US8462330B2 (en) 2005-06-22 2013-06-11 Hitachi High-Technologies Corporation Method and apparatus for detecting defects
US7751037B2 (en) 2005-06-22 2010-07-06 Hitachi High-Technologies Corporation Method and apparatus for detecting defects
US20060290923A1 (en) * 2005-06-22 2006-12-28 Hiroyuki Nakano Method and apparatus for detecting defects
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US20070263206A1 (en) * 2006-05-12 2007-11-15 Leblanc Philip Robert Apparatus and method for characterizing defects in a transparent substrate
US8094298B2 (en) 2006-07-07 2012-01-10 Hitachi High-Technologies Corporation Method for detecting particles and defects and inspection equipment thereof
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US20090066941A1 (en) * 2006-07-07 2009-03-12 Hitachi High-Technologies Corporation Method for detecting particles and defects and inspection equipment thereof
USRE44840E1 (en) 2006-07-07 2014-04-15 Hitachi High-Technologies Corporation Method for detecting particles and defects and inspection equipment thereof
USRE44977E1 (en) 2006-07-07 2014-07-01 Hitachi High-Technologies Corporation Method for detecting particles and defects and inspection equipment thereof
US20100020315A1 (en) * 2006-07-07 2010-01-28 Hitachi High-Technologies Corp Method for detecting particles and defects and inspection equipment thereof
WO2009142346A1 (fr) * 2008-05-19 2009-11-26 Semisysco Co., Ltd. Dispositif de contrôle des ondulations du verre et procédé de contrôle associé
US8823935B1 (en) * 2008-09-10 2014-09-02 Kla-Tencor Corporation Detecting and classifying surface defects with multiple radiation collectors
CN105572149A (zh) * 2010-01-29 2016-05-11 康宁精密素材株式会社 平板玻璃表面的异物检测装置
CN102141526A (zh) * 2010-01-29 2011-08-03 三星康宁精密素材株式会社 平板玻璃表面的异物检测装置
US20110187849A1 (en) * 2010-01-29 2011-08-04 Hyunwoo Kim Detection apparatus fo paricle on the glass
US20140185040A1 (en) * 2012-12-27 2014-07-03 Shenzhen China Star Optoelectronics Technology Co., Ltd. Mother glass inspection device and mother glass inspection method
US9140655B2 (en) * 2012-12-27 2015-09-22 Shenzhen China Star Optoelectronics Technology Co., Ltd. Mother glass inspection device and mother glass inspection method
US20160216214A1 (en) * 2015-01-27 2016-07-28 Cheng Mei Instrument Technology Co., Ltd. Panel inspection apparatus and method
CN105823780A (zh) * 2015-01-27 2016-08-03 政美应用股份有限公司 面板检测装置与方法
US9810640B2 (en) * 2015-01-27 2017-11-07 Cheng Mei Instrument Technology Co., Ltd. Panel inspection apparatus and method
CN105843436A (zh) * 2015-01-29 2016-08-10 政美应用股份有限公司 触控面板的检测方法及装置
US20240102940A1 (en) * 2020-12-14 2024-03-28 Isra Vision Ag Device for inspecting the surface of a transparent object, and corresponding method
US12498331B2 (en) * 2020-12-14 2025-12-16 Isra Vision Gmbh Device for inspecting the surface of a transparent object, and corresponding method
US20240377338A1 (en) * 2023-05-09 2024-11-14 Innolux Corporation Inspection method for electronic devices

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KR0159290B1 (ko) 1999-05-01
JPH0552762A (ja) 1993-03-02
DE69117714T2 (de) 1996-10-02
EP0493815B1 (fr) 1996-03-06
JP2671241B2 (ja) 1997-10-29
EP0493815A3 (en) 1992-10-14
EP0493815A2 (fr) 1992-07-08
DE69117714D1 (de) 1996-04-11

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